Murine Friend erythroleukemia cells grown in vitro undergo a series of differentiation changes after treatment with dimethylsulfoxide (DMSO) and butyric acid. These changes include a decrease in cell volume, a condensation of chromatin and the production of hemoglobin. This proposal is concerned with the characterization of the mouse fetal hemoglobin and the hemoglobins produced in the T3Cl2 Friend Leukemic Clone. In order to obtain a sufficient quantity of fetal blood, timed pregnant C57BL mice will be used between the 16-18th days of gestation. The hemoglobin will be purified by preparative isoelectric focusing and biochemically characterized. Peptide maps and partial amino acid sequencing will be made on the separated bands. The hemoglobins produced from the T3Cl2 clone by DMSO and butyric acid induction will be compared to those from the host DDD fetal and adult mice. After the existence of the two hemoglobins is established the differential production of two hemoglobins will be investigated by sequentially adding inducing agents and inhibitors. The modulation of hemoglobin expression will be studied by varying the in vitro growth conditions. The relationship of the degree of G1 block to hemoglobin expression will also be examined. The type of hemoglobins made in single cells induced by BA will be studied using specific purified antibodies to the two hemoglobins.